JPH0550845B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a resist pattern forming method for manufacturing high-density integrated circuits such as LSIs and VLSIs, and photomasks used for manufacturing them. The present invention relates to a resist pattern forming method for positive electron beam resist.

[Conventional technology]

As is well known, in recent years there has been an increasing demand for higher performance and higher integration of semiconductor integrated circuits and the like.
For this reason, efforts are being made to establish ultra-fine pattern processing technology using lithography using electron beams, soft X-rays, ion beams, etc., instead of photolithography using conventional ultraviolet rays. Electron beam lithography is already in practical use industrially in the production of photomasks.

In order to enable such ultra-fine lithography technology, the resist material used must have properties corresponding to it. or,
The resist plate-making process is also extremely important as it affects the quality of ultrafine processing.

In general, many types of electron beam resists have been developed. These are classified into positive resists, in which a disintegration reaction occurs when irradiated with an electron beam and the irradiated area becomes solubilized, and negative resists, in which a crosslinking reaction occurs when irradiated with an electron beam, and the irradiated area becomes insolubilized. be done. Of the two, positive resists are superior to negative resists in that they can form ultra-fine, high-resolution images.

However, among positive resists, 2,
Electron beam positive type mainly composed of halogenated alkyl methacrylate polymers such as 2,2-trichloroethyl methacrylate polymer, 2,2,2-trifluoroethyl-α-chloroacrylate polymer, and hexafluorobutyl methacrylate polymer. After a resist is applied to an arbitrary substrate, dried, a pattern is drawn with an electron beam, and developed with a prescribed developer, a resist residue with a thickness of about 10 to 100 Å remains on the surface of the substrate around the pattern. This method has the disadvantage that the smaller the pattern interval, the more the residual development of resist residue occurs.

Therefore, the resist residue significantly impairs the image quality of the resist pattern, becomes an obstacle in the next etching process, causes uneven etching and etching residue, and ultimately makes the product defective.

Therefore, resist patterns of conventional electron beam resists mainly composed of halogenated alkyl methacrylate polymers have been formed by the following method.

First, an electron beam resist of a certain thickness is applied onto a predetermined substrate and dried. Next, a pattern is drawn with an electron beam, and then developed with a predetermined developing solution to obtain a resist pattern. At this time, resist residue is generated around the pattern. Next, after post-baking to harden the resist, a descum process (or light ashing process) is performed to remove resist residue, so-called scum, using oxygen plasma gas in a dry etching device to remove the resist residue and form the desired resist. I'm getting a pattern. For this reason, conventional descam equipment requires a cylindrical or parallel plate type dry etching equipment, and its operation and condition settings are complex and require careful control, and the process is complicated because it uses a vacuum system. .

[Problem that the invention attempts to solve]

Therefore, the problem to be solved by the present invention is to provide a method for obtaining a high-quality resist pattern without the complicated descum process of dry etching using oxygen plasma or the like, which improves the above-mentioned drawbacks.

[Means for solving problems]

In order to solve the above problems, the inventor of the present invention has conducted research and found that processing should be carried out using a resist crude material that becomes positive type when irradiated with electron beams and also becomes positive type when irradiated with far ultraviolet rays. Forming a resist film on a substrate, drawing a pattern by electron beam irradiation, and then developing to generate a resist pattern,
Next, they discovered that the resist residue can be removed by irradiating the entire surface with deep ultraviolet rays for several minutes, and that the effect of removing resist residue can be further enhanced by irradiating the substrate with far ultraviolet rays while heating the substrate. The present invention was completed based on this.

That is, the gist of the first invention is to form a resist film on a substrate to be processed using a resist composition that becomes positive when irradiated with an electron beam and also becomes positive when irradiated with deep ultraviolet rays. Then, a pattern is drawn by electron beam irradiation, and then developed to generate a resist pattern, and then the entire surface is irradiated with deep ultraviolet rays to remove resist residue remaining around the pattern, and before the deep ultraviolet irradiation step or A resist pattern forming method is characterized in that the resist pattern is formed by post-baking to harden the resist. A resist film is formed on a substrate to be processed using a positive resist composition, a pattern is drawn by electron beam irradiation, and then developed to generate a resist pattern, and then the substrate is heated while A method for forming a resist pattern, which comprises irradiating the entire surface with deep ultraviolet rays to remove resist residue remaining around the pattern, and performing post baking to harden the resist before or after the deep ultraviolet irradiation step. It is.

The present invention will be explained in detail below.

As shown in FIG. 1a, a positive electron beam resist is spin-coated using a spinner or the like on a predetermined substrate 1 to be processed, such as a silicon wafer or a photomask blank, and dried to a thickness of 0.2 μm or more.
A uniform resist film 2 of 2 μm is obtained. The drying temperature and time for resists vary depending on the characteristics of each resist's polymer and solvent, but are generally 70℃~
150°C for 30 minutes is used.

As the positive resist used in the present invention, a general positive resist that requires a descum process is used.
2,2,3,4,4,4-hexafluorobutyl methacrylate (trade name: Daikin Industries)
FBM), poly-1,1-dimethyl-2,2,3,
3-tetrafluoropropyl methacrylate (trade name: Daikin Industries FPM), poly-2,2,2
- Polyhalogenated alkyl methacrylate resists such as trichloroethyl methacrylate (product name: Toray EBR-1), poly-2,2,2-trifluoroethyl-α-chloroacrylate (product name: Toray EBR-9), etc. can give.

Next, as shown in FIG. 1b, a pattern is drawn with an electron beam 3, and developed with a predetermined developer, and as shown in FIG. 1c,
Resist pattern 4 is obtained. At this time, in the positive type resist which requires a descum process used in the present invention, resist residue 5 is generated around the pattern.
As the developer, a predetermined developer for each resist is used.

Next, as shown in FIG. 1d, the resist pattern 4 is
wavelength from the pattern side to the entire surface of the substrate 1 having
The entire surface is irradiated with far ultraviolet rays 6 of 180 nm to 300 nm.
The irradiation time varies slightly depending on the resist used, the irradiation wavelength, and the output of the light source, but several minutes to several tens of minutes can be applied. The resist residue (scum) 5 is removed by irradiation with deep ultraviolet rays 6, and a desired good resist pattern 7 free of resist residue is formed as shown in FIG. 1e. After FIG. 1e, the normally performed resist steps, ie, a post-bake step, a substrate etching step, and a resist stripping step, are sequentially performed.

In the present invention, the post-baking step may be performed before the deep ultraviolet irradiation step.

In the present invention, the resist residue can be removed more effectively by performing the step of removing the resist residue by irradiation with deep ultraviolet rays in an oxygen atmosphere.

The above is a description of the method of the first invention.

Next, the method of the second invention will be explained.

The method of the second invention differs from the method of the first invention only in that the irradiation with deep ultraviolet rays is carried out while heating the substrate to 50 to 150°C, and the other configurations are the same as the configuration of the first invention. be.

Heating the substrate accelerates the removal of resist residue. In this case, the heating temperature varies depending on the type of resist used, but in order not to reduce the resolution of the resist pattern, it is necessary to keep it below the glass transition temperature of each resist. Moreover, the appropriate irradiation time is several minutes to 10 minutes.

[Effect]

The resist residue 5 is removed by irradiation with deep ultraviolet rays 6. Although the details of the mechanism by which this resist residue is removed are not clear, it is presumed as follows. Resist residue (scum) of polyhalogenated alkyl methacrylate, which is a positive type resist, is a compound whose molecular weight has been reduced due to main chain scission of the resist due to electron beam irradiation. By irradiating this scum with deep ultraviolet rays, which are high-energy rays, the scum, which has lowered its molecular weight, further decomposes, producing volatile substances such as hydrogen, carbon dioxide, carbon monoxide, methane, and halogen gas. It is thought that it will be distilled off.

〔Example〕

Next, examples of the present invention will be described.

Example 1 Poly-2,2, on a chrome mask blank substrate
3-4,4,4-Hexafluorobutyl methacrylate-based resist (trade name FBM-120 manufactured by Daikin Industries) was applied with a spinner, and 140
Prebaking was performed at ℃ for 30 minutes to obtain a resist film with a thickness of 0.5 μm. Next, a pattern is drawn using an electron beam exposure device and a special developer (product name FBM-120D) is used to draw the pattern.
Spray development was performed at 23°C for 60 seconds, and spray rinsing was performed at 23°C for 30 seconds using a special rinsing liquid (trade name: FBM-120R) to obtain a resist pattern. This resist pattern shows resist residue (scum) under an optical microscope.
The existence of was recognized.

Next, it emits far ultraviolet rays with a wavelength of 190nm to 250nm.
The entire surface of the resist pattern was irradiated with a 500 W Xe-Hg lamp at a distance of 50 cm at room temperature for about 3 minutes in the atmosphere.

When this fully irradiated resist pattern is observed again under an optical microscope, resist residue (scum) can be seen.
was completely removed, and it was confirmed that a good resist pattern was formed.

Next, post-baking at 80℃ for 30 minutes, and diluted with nitric acid.
Wet etching was performed for 40 seconds with a cerium ammonium aqueous solution, and the chromium was etched according to the resist pattern. Next, the resist was removed using oxygen plasma to obtain a patterned chrome photomask.

Example 2 A resist containing poly-2,2,2-trifluoroethyl-α-chloroacrylate as a main component (trade name, Toray EBR-9) was coated with a spinner on a two-layer chrome mask blank substrate with low surface reflection. , 200
A resist film was obtained by prebaking at ℃ for 30 minutes.
Next, a pattern was drawn using an electron beam, and the resist pattern was developed and rinsed using a special developer and a rinsing solution to obtain a resist pattern.

Next, while heating the substrate to 80°C on a hot plate, the entire surface of the resist pattern was irradiated with a 400W deuterium lamp from a distance of 30cm in the air for about 3 minutes to form a pattern with no resist residue (scum) removed. .

〔Effect of the invention〕

As detailed above, according to the method of the present invention, resist residue can be easily removed without using a dry etching device.

[Brief explanation of the drawing]

1a to 1e are schematic diagrams showing the steps of the method of the present invention. 1...Substrate, 2...Resist film, 3...Electron beam, 4...Resist pattern, 5...Resist residue, 6...Deep ultraviolet rays.

Claims (1)

[Scope of Claims] 1. Forming a resist film on a substrate to be processed using a resist composition that becomes positive when irradiated with an electron beam and becomes positive when irradiated with deep ultraviolet rays, Draw a pattern by electron beam irradiation, then develop to generate a resist pattern, and then irradiate the entire surface with deep ultraviolet rays to remove resist residue remaining around the pattern, and before or after the deep ultraviolet irradiation process. A method for forming a resist pattern, which comprises curing the resist by post-baking. 2. The method for forming a resist pattern according to claim 1, wherein the resist composition is a resist composition made of a polymer selected from the group consisting of polyhalogenated alkyl methacrylates. 3. The method for forming a resist pattern according to claim 1 or 2, wherein the irradiation with deep ultraviolet rays is performed in an oxygen atmosphere. 4 Using a resist composition that becomes positive when irradiated with an electron beam and also becomes positive when irradiated with deep ultraviolet rays, a resist film is formed on the substrate to be processed, and a pattern is formed by irradiation with an electron beam. drawing and then developing to produce a resist pattern;
Next, while heating the substrate, the entire surface is irradiated with deep ultraviolet rays to remove resist residue remaining around the pattern, and post-baking is performed before or after the deep ultraviolet irradiation process to harden the resist. A method for forming a resist pattern. 5. The method for forming a resist pattern according to claim 4, characterized in that the resist composition is a resist composition made of a polymer selected from the group consisting of polyhalogenated alkyl methacrylates. 6. The method of forming a resist pattern according to claim 4 or 5, wherein the irradiation with far ultraviolet rays is performed in an oxygen atmosphere.